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Southern Bacterial Wilt
Ralstonia solanacearum (Smith) Yabuuchi et al.
Southern bacterial wilt (or bacterial wilt) is a destructive
disease of tomato and other solanaceous crops as well as a wide
range of ornamentals. This disease is caused by the soil-borne
bacterium Ralstonia solanacearum, which attacks over 200 plant
species in more than 50 plant families. The bacterium enters
plant roots through wounds and disease development is favored
by high temperatures and wet soils. The pathogen is spread
within fields by the movement of infested soil, in surface water
and though the handling of infected plants.
Initial symptoms of southern bacterial wilt are a loss of turgidity of leaves and stems, giving the plants a limp appearance. In
the early stages, these plants may recover overnight, but as the
disease continues to develop, this is followed rapidly by drying of
the leaves and permanent wilting and death of the plant. Brown,
sunken cankers are often visible at the base of the plant; this is
accompanied by discoloration of the vascular system and eventually the pith. A brown rot of the roots may also be observed.
Ralstonia solanacearum exists as a number of races and
biovars that are differentiated based primarily on host range
and geographic distribution. Race 1 affects a wide variety of
plants, including tomato and other solanaceous crops; race1
biovar 1 is the strain endemic to the southeastern U.S. Ralstonia
solanacearum race 3 biovar 2 occurs throughout much of the
world but is not currently present in the U.S. and Canada. This
strain grows at cooler temperatures than our native strain and
is a major problem on potatoes and other solanaceous crops as
well as ornamentals, most notably geraniums. Quarantines are in
effect to prevent its accidental introduction.
Management of southern bacterial wilt presents a real
challenge. Soil fumigation may reduce the incidence of disease
early in the season, but it has not provided long-term control.
Recommendations for the management of southern bacterial
wilt include avoid planting susceptible crops in infested fields,
avoid late plantings of tomatoes in areas know to be infested
and use of long-term rotations with non-host crops (such as
corn, beans and cabbage). There are no commercially available
resistant/tolerant varieties that we can recommend.
Fig. 1. Progression of symptoms of southern
bacterial wilt of tomato.
Fig. 2. Basal canker and internal discoloration of the stem due to southern bacterial wilt.
Fig. 3. Bacterial streaming from
an infected tomato stem.
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Author
Dr. Donald M. Ferrin
Department of Plant Pathology
and Crop Physiology
Photo Credits
Dr. Donald M. Ferrin
Louisiana State University Agricultural Center, William B. Richardson, Chancellor
Louisiana Agricultural Experiment Station, John R. Russin,Vice Chancellor and Director
Louisiana Cooperative Extension Service, Paul D. Coreil,Vice Chancellor and Director
Pub. 3190
(online only)
07/11
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